A gas turbine engine has several modules. The first module, in terms of axial flow path, is the compressor section. Ambient air enters the engine through the compressor section. The compressor section pressurizes the air.
The second module is the combustion section. The combustion section introduces fuel to the air previously compressed by the compressor section. The combustion section then ignites the mixture.
The third module is the turbine section. The turbine section extracts energy from the exhaust produce by the compressor section. The turbine section is coupled to the compressor section so that the exhaust drives the compressor.
Finally, the air exits the engine as thrust.
FIG. 1 is a perspective view of part of a gas turbine engine 210. The drawing shows a first module, such as a compressor section 211, adjacent a second module, such as a combustion section 213. The cases of these sections 211, 213 have corresponding flanges 215, 217 which abut and define a joint 219.
Fasteners, such as 12-point bolts 221 and nuts 223, extend through aligned openings in the flanges 215, 217 to seal the joint 219. FIG. 1 displays the conventional method of tightening the bolts 221 and nuts 223. The typical method requires the operator first to manipulate both a manual wrench W and a pneumatic impact wrench I. The manual wrench W engages the nut 223 and the pneumatic wrench I engages the bolt 221. After actuating the impact wrench I, the operator prevents rotation of the nut 223 by applying torque to the wrench W. As the bolt 221 and nut 223 tighten, the operator must apply an increasing amount of torque to the wrench W. The operator replaces the impact wrench I with another manual wrench W to provide the final torque to the fasteners. Now, the operator must apply torque to both manual wrenches W.
Loosening the bolts 221 and nuts 223 is similar. The operator engages the nut 223 with the wrench W and the bolt 221 with the second manual wrench W. The operator applies torque to both manual wrenches to loosen the fasteners slightly. Then operator then replaces the second manual wrench W with the impact wrench I. The operator then actuates the impact wrench I to remove the loosened bolt 221. The operator applies the greatest amount of torque to the wrench W during initial loosening of the fasteners. As the bolt 221 and the nut 223 loosen further, the operator can apply a decreasing amount of torque to the wrench W.
The operator must apply a typical torque of between approximately 30 and approximately 1000 in-lbs. Since the joint 19 may have up to 160 pairs of bolts 221 and nuts 223, the possibility of operator fatigue does exist. Since the engine 210 may have at least four joints 219, the possibility of fatigue becomes even more apparent.